RFR(XXS): 8169630: Fix wrong cpu build flag for Linux/ppc64le build

[Volker Simonis]

Hi,

can somebody please review and sponsor the following tiny build fix
which only affects ppc64le but requires the re-generation of
generated-config.sh:

http://cr.openjdk.java.net/~simonis/webrevs/2016/8169630/
https://bugs.openjdk.java.net/browse/JDK-8169630

On ppc64le we use "-mcpu=power7 -mtune=power8" for historical reasons,
but the first Power CPU with "real" little-endian support is Power8 so
this should be changed to "-mcpu=power8 -mtune=power8".

Thank you and best regards,
Volker

PS: @Erik - I promise, this is the last build change for today :)